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Ferroelectrics 343 (2006) 101-110
X-Ray and Electrooptical Studies of Liquid Crystal Siloxane with a de Vries SmA* Phase
F. Goc1, 2, C. Blanc1, 2, V. Lorman1, 2, M. Nobili1, 2, S. Samaritani, G. Galli, W. Kuczynacuteski

We present the X-ray diffraction, polarizing optical microscopy and electrooptic response studies of the chiral liquid crystal siloxane DSi3-MR11 [1] with a de Vries-type behavior. In a wide temperature range (b.Delta T sim 50°C) the material shows no layer shrinkage but a weak nearly linear layer spacing variation with temperature. Neither discontinuity nor slope change occurs at the SmA*-SmC* transition. In addition, using the X-ray data, the unusual electrooptic response in both 1st and 2nd harmonics together with known thermal behavior of birefringence, we evidence the cross-over from the classical orthogonal to the de Vries-like SmA* regime in DSi3-MR11 siloxane.
1 :  LCVN - Laboratoire des colloïdes, verres et nanomatériaux
2 :  LPTA - Laboratoire de Physique Théorique et Astroparticules
Physique/Matière Condensée/Science des matériaux
de Vries – smectic A* phase – X-ray – optics – electrooptics